The development of synchronization (coordination) of movement between the left and right wing of the chick Gallus domesticus will be described from 9 days of embryonic development until 28 days after hatching. This will be one of the first studies to quantitatively examine the ontogeny of bilateral coordination in the chick. A behavioral study will describe the amount, periodicity and degree of concurrent spontaneous and evoked wing activity at the 9-, 13-, and 17-day embryonic stages. A higher resolution analysis of the synchronization of wing movement will be carried out using extra-cellular electromyographic (EMG) recordings from the pectoral muscles which are responsible for the wing downstroke during flight. After hatching, wing movements will be evoked by dropping a chick a standard distance of 6 ft. The behavorial and EMG, descriptive procedures to be developed for this research, may be utilized in subsequent experimental studies of chick motor development.